Dan Baldwin Posted January 22, 2003 Share Posted January 22, 2003 Unshaved, that'd put you at 9.8:1 CR. No problem. I ran over 10.2:1 with the stock cam in my N42-headed 3.1 liter for years with no problems. You will want to use premium fuel, though. Bringing your CR up to a decent level is one of the best things you can do for a NA Z, IMO. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted January 22, 2003 Author Share Posted January 22, 2003 Oh yeah a mild cam will be part of the equation Quote Link to comment Share on other sites More sharing options...
Mudge Posted January 22, 2003 Share Posted January 22, 2003 Bad gas and timing can create ping, or were you talking about a poor combustion chamber design? N42 is pretty commonly used so I dont see a problem with it. If you run too much timing there will be issues, just the way it goes. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted January 23, 2003 Author Share Posted January 23, 2003 I always thougt it was OK until I read this. Check this out and read the portion that talks about pinging and the N47. The following quote was "taken" from this site: www.geocities.com/zgarage2001/head.html I won't pretend to know everything about those heads, but I posed that question to the Z Doc who I trust. He said those 2 heads are widely used, but can ping easilyon flattop motors as their low quench chambers are designed for dished pistons. This shape lets the flame kernel spread away from the spark plug and ignite. For a good budget racer, probably not a bad idea, just be ready to use some octane booster BTW, the Doc races an E31 with larger 280 valves on a flattop motor and says it runs "right on the edge of pinging. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted January 23, 2003 Author Share Posted January 23, 2003 Never mind. After doing a good search I found all the info I needed and then some. I feel smarter already. Thanks to all. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted January 23, 2003 Author Share Posted January 23, 2003 I am considering increasing compression ratio by installing a N47 head to my F54 block. I hear that using a F54 block with the flat pistons mated to a N42/N47 head can most certainly cause pinging problems. Anybody out there with this setup that can give his/her opinion/experience Quote Link to comment Share on other sites More sharing options...
yo2001 Posted January 23, 2003 Share Posted January 23, 2003 You can always get a bigger cam Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 24, 2003 Share Posted January 24, 2003 I'm building such a motor (F54, N47). Just put the head on last night. Want to share any of the information you have discovered? Pete Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted January 25, 2003 Author Share Posted January 25, 2003 Well Pete, Basically from what I have read the easiest way to improve CR is to use the N47/N42 with the F54 block. Some of the guys here say that you can get as good or better performance off of a modified P79. To do this you need a good shop to do all the work and relatively deep pockets. There are postings about this topic for days. If you are like me, (champagne taste, beer pockets) then forget about the P79 and work with the N42 or N47. Its quick, it's easy and for the money, you cant beat it. I just got laid-off from work. That really puts a cramp on the spending. Let me know how yours turns out. I'll let you know about mine as soon as I get it done. Quote Link to comment Share on other sites More sharing options...
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